Global Spinal Alignment in Cervical Kyphotic Deformity: The Importance of Head Position and Thoracolumbar Alignment in the Compensatory Mechanism

BACKGROUND

Previous studies have evaluated cervical kyphosis (C-kypho) using cervical curvature or chin-brow vertical angle, but the relationship between C-kypho and global spinal alignment is currently unknown.

OBJECTIVE

To elucidate global spinal alignment and compensatory mechanisms in primary symptomatic C-kypho using full-spine radiography.

METHODS

In this retrospective multicenter study, symptomatic primary C-kypho patients (Cerv group; n = 103) and adult thoracolumbar deformity patients (TL group; n = 119) were compared. We subanalyzed Cerv subgroups according to sagittal vertical axis (SVA) values of C7 (SVAC7 positive or negative [C7P or C7N]). Various Cobb angles (°) and SVAs (mm) were evaluated.

RESULTS

SVAC7 values were –20.2 and 63.6 mm in the Cerv group and TL group, respectively (P < .0001). Various statistically significant compensatory curvatures were observed in the Cerv group, namely larger lumbar lordosis (LL) and thoracic kyphosis. The C7N group had significantly lower SVACOG (center of gravity of the head) and SVAC7 (32.9 and –49.5 mm) values than the C7P group (115.9 and 45.1 mm). Sagittal curvatures were also different in T4-12, T10-L2, LL4-S, and LL. The value of pelvic incidence (PI)-LL was different (C7N vs C7P; –2.2° vs 9.9°; P < .0003). Compensatory sagittal curvatures were associated with potential for shifting of SVAC7 posteriorly to adjust head position. PI-LL affected these compensatory mechanisms.

CONCLUSION

Compensation in symptomatic primary C-kypho was via posterior shifting of SVAC7, small T1 slope, and large LL. However, even in C-kypho patients, lumbar degeneration might affect global spinal alignment. Thus, global spinal alignment with cervical kyphosis is characterized as head balanced or trunk balanced.

Pre-Operative Autologous Blood Donation Does Not Affect Pre-Incision Hematocrit in Adolescent Idiopathic Scoliosis Patients. A Retrospective Cohort of a Prospective Randomized Trial

BACKGROUND

Pre-donation of autologous blood prior to spine fusion for adolescent idiopathic scoliosis (AIS) has been used in deformity surgery. The effect of pre-donation on pre-operative hematocrit (Hct) remains debated. Multiple factors may influence pre-operative Hct including intravascular volume status, patient factors, and timing of pre-operative blood donation. The purpose of this study was to determine if pre-donation significantly lowers pre-incision Hct in AIS patients.

METHODS

A retrospective cohort study of a Level-1 prospective randomized trial was conducted. 125 patients from the homogeneous population were included. AIS patients undergoing a posterior only spinal fusion for AIS were separated into two groups based on their pre-operative blood donation history. Demographic variables, pre-incision Hct, and transfusion rates were compared between the two groups using the Student's T-test.

RESULTS

Pre-donation and non pre-donation groups had 28 and 97 patients, respectively. Pre-donation group was 75% female (21F, 7M) and non pre-donation group was 78% female (76F, 21M). There was no difference between pre-donation and non pre-donation groups in mean age (15.6 ± 2.2 vs 14.8 ± 2.2, p = 0.081), BMI (23.1 ± 4.2 vs 21.7 ± 5.3, p = 0.219), and pre-incision Hct (32.8 ± 3.4 vs 33.8 ± 3.1, p = 0.628). The overall transfusion rates were equivalent (32.1± 48.0% vs 25.8 ± 44.0%, p = 0.509), however, the rate of allogenic transfusion for the pre-donation group was significantly lower (3.6 ± 18.9% vs 25.8 ± 44.0%, p = 0.011).

CONCLUSIONS

This study supports the use of pre-donation for AIS, without a significant drop in pre-incision Hct. Patients that donate are also much less likely to be exposed to allogenic blood. There may be a surgeon bias to recommend pre-donation in patients with a larger BMI and older age. Future studies are needed from a larger population of patients including those with non-AIS pathology.

LEVEL OF EVIDENCE

Level III.

Does borazine-water behave like benzene-water? A matrix isolation infrared and ab initio study

Borazine is isoelectronic with benzene and is popularly referred to as inorganic benzene. The study of non-covalent interactions with borazine and comparison with its organic counterpart promises to show interesting similarities and differences. The motivation of the present study of the borazine-water interaction, for the first time, stems from such interesting possibilities. Hydrogen-bonded complexes of borazine and water were studied using matrix isolation infrared spectroscopy and quantum chemical calculations. Computations were performed at M06-2X and MP2 levels of theory using 6-311++G(d,p) and aug-cc-pVDZ basis sets. At both the levels of theory, the complex involving an N-H⋯O interaction, where the N-H of borazine serves as the proton donor to the oxygen of water was found to be the global minimum, in contrast to the benzene-water system, which showed an H-π interaction. The experimentally observed infrared spectra of the complexes corroborated well with our computations for the complex corresponding to the global minimum. In addition to the global minimum, our computations also located two local minima on the borazine-water potential energy surface. Of the two local minima, one corresponded to a structure where the water was the proton donor to the nitrogen of borazine, approaching the borazine ring from above the plane of the ring; a structure that resembled the global minimum in the benzene-water H-π complex. The second local minimum corresponded to an interaction of the oxygen of water with the boron of borazine, which can be termed as the boron bond. Clearly the borazine-water system presents a richer landscape than the benzene-water system.

Medicare Reimbursement for Total Joint Arthroplasty: The Driving Forces

BACKGROUND

Total joint arthroplasty is a large and growing part of the U.S. Medicare budget, drawing attention to how much providers are paid for their services. The purpose of this study was to examine the variables that affect total joint arthroplasty reimbursement. Along with standard economic variables, we include unique health-care variables. Given the focus on value in the Affordable Care Act, the model examines the relationship of the quality of care to total joint arthroplasty reimbursement. We hoped to find that reimbursement patterns reward quality and reflect standard economic principles.

METHODS

Multivariable regression was performed to identify variables that correlate with Medicare reimbursement for total joint arthroplasty. Inpatient charge or reimbursement data on Medicare reimbursements were available for 2,750 hospitals with at least 10 discharges for uncomplicated total joint arthroplasty from the Centers for Medicare & Medicaid Services (CMS) for fiscal year 2011. Reimbursement variability was examined by using the Dartmouth Atlas to group institutions into hospital referral regions and hospital service areas. Independent variables were taken from the Dartmouth Atlas, CMS, the WWAMI (Washington, Wyoming, Alaska, Montana, Idaho) Rural Health Research Center, and the United States Census.

RESULTS

There were 427,207 total joint arthroplasties identified, with a weighted mean reimbursement of $14,324.84 (range, $9,103 to $38,686). Nationally, the coefficient of variation for reimbursements was 0.19. The regression model accounted for 52.5% of reimbursement variation among providers. The total joint arthroplasty provider volume (p < 0.001) and patient satisfaction (p < 0.001) were negatively correlated with reimbursement. Government ownership of a hospital (p < 0.001) and higher Medicare costs (p < 0.001) correlated positively with reimbursement.

CONCLUSIONS

Medicare reimbursements for total joint arthroplasty are highly variable. Greater reimbursement was associated with lower patient volume, lower patient satisfaction, a healthier patient population, and government ownership of a hospital. As value-based reimbursement provisions of the Affordable Care Act are implemented, there will be dramatic changes in total joint arthroplasty reimbursements. To meet these changes, providers should expect qualities such as high patient volume, willingness to care for sicker patient populations, patient satisfaction, safe outcomes, and procedural demand to correlate with their reimbursement.

CLINICAL RELEVANCE

Practicing orthopaedic surgeons and hospital administrators should be aware of discrepancies in inpatient reimbursement for total joint arthroplasty from Medicare. Furthermore, these discrepancies are not associated with typical economic factors. These findings warrant further investigation and collaboration between policymakers and providers to develop value-based reimbursement.

A Comparison of Two Different Dosing Protocols for Tranexamic Acid in Posterior Spinal Fusion for Spinal Deformity: A Prospective, Randomized Trial

BACKGROUND

Multilevel spinal fusions have typically been associated with significant blood loss. Previous studies have shown a reduction in blood loss with antifibrinolytics in both adolescent and adult spinal deformity patients. While this has been mirrored in other subspecialties as well, the dosing of TXA remains highly variable. To date, there remains a paucity of data guiding dosing for TXA in spine surgery and orthopedic surgery as a whole.

METHODS/DESIGN

One hundred and fifty patients from 3 institutions (50 each site) will be consecutively enrolled and randomized to either a high dose of TXA (50mg/kg loading followed by 20mg/kg hourly) or a lose dose (10mg/kg, then 1mg/kg hourly). Both surgeons and patients will be blinded to the treatment group. Primary outcomes will be perioperative blood loss, drain output, and transfusion rate. Secondary outcomes will be length of stay, complications, and overall cost.

DISCUSSION

The primary goal of this study is to provide level-1 comparative data for two TXA dosing regimens in adult spinal deformity surgery. Management of blood loss remains a critical factor in reducing complications during spinal deformity surgery. The null hypothesis is that there is no difference between high- and low-dose TXA with respect to any of the primary or secondary outcomes.

Spinal metastasis of breast cancer presenting after 25 years: An extremely rare presentation

Breast cancer is the most frequently diagnosed cancer in females of the developed world and is gradually becoming the leading cause in the developing world as well. The innate biology of breast cancer is marked by varied presentations, characteristics, response, recurrence and metastatic phenomenon. Even an early stage breast cancer has the potential to recur and/or metastasize after extremely long duration and this possibility should be borne in the clinician's mind.

Spinal Dural Arteriovenous Fistula Presenting as a Recurrent Nucleus Pulposus Herniation: A Case Report and Literature Review

CASE

Of the many potential causes of nerve compression that lead to radiculopathy, vascular etiologies remain among the most infrequent, with an estimated prevalence of only five to ten per million cases of radiculopathy. In this case report, we outline the clinical presentation, imaging, intraoperative findings, and pathologic findings for a fifty-four-year old patient with an intradural, extramedullary form of a spinal dural arteriovenous fistula at the L1-L2 level who presented only with axial back pain and radiculopathy. The radiologist and surgeon initially diagnosed the patient with a herniated nucleus pulposus. However, the intraoperative findings and angiogram were suggestive of an arteriovenous fistula. Methods to identify this rare entity are described for the orthopaedic spine community.

CONCLUSION

The potential for a missed diagnosis is particularly important as many partial discectomy procedures are performed at small surgical centers with limited blood products available and no vascular surgeon on staff. For patients with preoperative magnetic resonance imaging (MRI) that is suggestive of vascular malformations (T2 hyperintensity in the lower spinal cord and conus medullaris), we recommend that MR angiography be performed as a secondary diagnostic evaluation. MR angiography has a 95% positive predictive value for specifically diagnosing an arteriovenous fistula.

Radiographic Outcomes of Postoperative Taping Following Hallux Valgus Correction

BACKGROUND

Traditionally, hallux valgus operative correction has been accompanied by serial spica taping of the great toe during the postoperative period.

METHODS

We retrospectively reviewed 187 adult patients who underwent proximal first metatarsal osteotomy with a modified McBride procedure in 2008-2009 (n = 83) and 2011-2012 (n = 104). Postoperatively, to maintain the corrected position of the hallux, patients from 2008 through 2009 underwent weekly spica taping, while patients from 2011 through 2012 utilized a toe separator. The hallux valgus angle (HVA) and intermetatarsal angle (IMA) were measured using anteroposterior weight-bearing preoperative, 2-week postoperative non-weight-bearing, and 3-month weight-bearing final follow-up radiographs. A mixed-effects linear regression model identified differences between the treatment groups over time, and a t test compared actual radiographic differences at final follow-up.

RESULTS

The mixed-effects model revealed no significant difference in the HVA over time when comparing patients taped to those not taped at the preoperative (33 ± 6 vs 33 ± 6), 2-week postoperative (10 ± 7 vs 9 ± 6), and 3-month follow-up (14 ± 6 vs 11 ± 7) visits (P = .08). At final follow-up, the HVA was lower for the group that was not taped, but the difference (2.5 degrees) was below the minimal clinically important difference (MCID) (P = .015, 95% CI 0.5-4.5). For IMA, there was improved maintenance of correction over time in the patients that were not taped compared to those taped at the preoperative (15 ± 3 vs 15 ± 3), 2-week postoperative (2 ± 2 vs 3 ± 3), and 3-month follow-up (5 ± 4 vs 7 ± 4) visits (P = .002). At final follow-up, the IMA was lower for the group that was not taped, but the difference (1.7 degrees) was below the MCID (P = .004, 95% CI 0.7-2.9).

CONCLUSIONS

We report no radiographic benefit of postoperative taping after hallux valgus correction. The present study challenges the previous dogma of postoperative spica taping as the protocol is cost and time intensive for the patient and surgeon.

LEVEL OF EVIDENCE

Level III, comparative series.

Vertebral body replacement by posterior approach for metastatic disease in the thoracic spine--modified technique using an expandable cage

OBJECTIVE

To describe the technique of all-posterior vertebral body replacement using an expandable cage and angled instruments. This method facilitates implant seating with limited posterior decompression useful in the setting of metastatic disease.

INDICATIONS

Patients with metastatic disease of the thoracic spine with or without spinal cord compression.

CONTRAINDICATIONS

Patients with a limited life expectancy of less than 6 months. Multiple foci of metastatic disease in the spine.

SURGICAL TECHNIQUE

A hemilaminectomy was performed followed by nerve root sacrifice. The pleura was mobilized away from the vertebral body, after which decompression and tumor resection was performed from an all-posterior approach. An expandable vertebral body cage was inserted with a rotational manoeuvre and expanded in situ.

POSTOPERATIVE MANAGEMENT

The patient was mobilized on postoperative day 1. A chest X-ray is also recommended to exclude incidental pneumothorax.

RESULTS

Four patients were operated by an all-posterior vertebral body replacement during a 6-month period. The average length of surgical procedure was 187 min (range 165-220 min). No patient required a transthoracic approach. There were no intra- or postoperative complications and all patients could be discharged to home self-ambulating.

The relative efficacy of antifibrinolytics in adolescent idiopathic scoliosis: a prospective randomized trial

BACKGROUND

Antifibrinolytics can reduce intraoperative blood loss. The primary aim of this study was to determine the efficacy of intraoperative tranexamic acid, epsilon-aminocaproic acid, and placebo at reducing perioperative blood loss and the transfusion rate in patients with adolescent idiopathic scoliosis undergoing posterior spinal arthrodesis.

METHODS

This is a prospective, randomized, double-blind comparison of tranexamic acid, epsilon-aminocaproic acid, and placebo used intraoperatively in patients with adolescent idiopathic scoliosis. One hundred and twenty-five patients with adolescent idiopathic scoliosis were randomly assigned to the tranexamic acid, epsilon-aminocaproic acid, or control groups. Parameters recorded included estimated blood loss, hematocrit, blood product usage, drain output, and total blood losses. The primary outcomes were intraoperative blood loss and postoperative drainage. Secondary outcomes were transfusion requirements and hematocrit changes both intraoperatively and postoperatively.

RESULTS

One hundred and twenty-five patients (ninety-seven female and twenty-eight male, with a mean age of fifteen years) were randomized to receive tranexamic acid (thirty-six patients), epsilon-aminocaproic acid (forty-two patients), or saline solution (forty-seven patients). The groups were similar at baseline, with one exception: the saline solution group had a higher estimated blood volume at baseline than the tranexamic acid group. Both tranexamic acid and epsilon-aminocaproic acid reduced the estimated blood loss per degree and estimated blood loss per pedicle screw. Epsilon-aminocaproic acid, but not tranexamic acid, reduced estimated blood loss and estimated blood loss per level. Tranexamic acid also reduced total blood losses compared with epsilon-aminocaproic acid or saline solution. In an analysis controlling for level, degree, and number of anchors, tranexamic acid reduced drain output and total blood losses. Tranexamic acid or epsilon-aminocaproic acid had a smaller decrease in hematocrit postoperatively. In an analysis controlling for the mean arterial pressure during surgical exposure, tranexamic acid reduced estimated blood loss and total blood losses. Overall, antifibrinolytics (tranexamic acid or epsilon-aminocaproic acid) reduced estimated blood loss, total blood losses, and the decline in hematocrit postoperatively compared with saline solution. There was no difference among the groups with respect to the transfusion rate, duration of surgery, levels fused, or pedicle screws placed.

CONCLUSIONS

Tranexamic acid and epsilon-aminocaproic acid reduced operative blood loss but not transfusion rate. Tranexamic acid is more effective at reducing postoperative drainage and total blood losses compared with epsilon-aminocaproic acid. Maintenance of the mean arterial pressure at &lt;75 mm Hg during surgical exposure appears to be critical for maximizing antifibrinolytic benefit.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Delayed Abdominal Compartment Syndrome as a Complication of Spinal Surgery: Literature Review and Case Report

Posterior spinal fusion surgery for neuromuscular scoliosis is associated with favorable outcomes and high caregiver satisfaction scores. However, these patients represent a medically fragile patient population prone to complications. One of the more unpredictable complications is abdominal compartment syndrome (ACS), the etiology of which is not fully understood. This case report represents the first case report of delayed ACS to develop 3 days after spinal fusion in a patient with no history of previous abdominal surgeries undergoing correction for neuromuscular scoliosis. This case outlines the clinical course, risk factors for ACS, and indications for urgent surgical decompression of the abdomen. Given the high mortality, it is important for orthopedic surgeons to understand prevention, presentation, and timely management associated with ACS.

Reduction of Mean Arterial Pressure at Incision Reduces Operative Blood Loss in Adolescent Idiopathic Scoliosis

BACKGROUND

Spinal fusion surgery for adolescent idiopathic scoliosis (AIS) has been associated with significant blood loss and transfusion requirements. Reduction of mean arterial pressure (MAP) has benefits, but has been debated. This study aimed to analyze hypotensive anesthesia (MAP less than 65 mm Hg) at incision for its effect on blood loss.

METHODS

Retrospective analysis of 327 AIS patients treated by a single surgeon from 2000 to 2008. We recorded demographic, laboratory, and radiographic measurements and perioperative data, including complications. We estimated MAP from the anesthesia flow sheet at incision (I-MAP) and during the entire surgery (Avg MAP). Patients were stratified into 3 groups: low (MAP less than 65), medium (MAP 65-75), or high (MAP greater than 75). We also evaluated the effect of elevated blood pressure at incision. The groups were as follows: reduced (I-MAP less than Avg MAP), stable (I-MAP = Avg MAP), or elevated (I-MAP greater than Avg MAP). We performed comparisons using analysis of variance with Tukey's Multiple Comparison Test. Blood loss was recorded as absolute volume and percent total blood volume (%EBV).

RESULTS

Of the 327 patients (mean age, 15 years; range, 10-21 years; 248 females), 129 received blood transfusions (29% allogenic). There was a reduction in blood loss comparing low (584 mL; 14% EBV) versus high I-MAP (871 mL; 20.3% EBV) (p = .03). Likewise, an elevated blood pressure at incision led to increased blood loss: reduced, 510 mL, 11.5% EBV; stable, 735 mL, 17.6% EBV; and elevated, 1,033 mL, 24.9% EBV (p = .000-.02). Operative time was decreased in the low group by up to 48 minutes (p = .002), as was blood loss per minute (2.6 mL/min vs. 3.8 mL/min). There were no complications related to the use of hypotension.

CONCLUSIONS

Induction of hypotensive anesthesia (MAP less than 65 mm Hg) at incision reduces operative blood loss by 33%. In addition, elevations in blood pressure at incision increase blood loss by 29%, and operative time by 29 minutes.